WAEC Physics 2020 Objective — Question 17
Question 17 of 50 from the West African Examinations Council (WAEC) Physics 2020 Objective paper, with the correct answer and a full explanation.
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A 60 kg man stands on a weighing balance in an elevator. If the elevator accelerates upwards at 5 ms^-2, determine the reading of the scale. [g=10ms^-2]
- A. 300 N
- B. 600 N
- C. 800 N
- D. 900 NCorrect
Explanation
Free body diagram: since the acceleration is upward, T-mg=ma, thus T=m(a+g)=60(5+10)=60x15=900N. The scale reading is greater than the weight (600N) of the man since the elevator accelerates upward.
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